Suction drawn from inside a hollow block wall, with the top course sealed. The piece a slab-only system misses on block foundations.
Owners here run into this regularly, and what the right answer is depends heavily on what the building is sitting on.
When this is the right question
- A hollow concrete-block foundation wall
- A system that was installed under the slab and only got the reading part of the way down
- Radon entering high on the wall rather than at the floor
- An older block wall with an open top course
What a certified crew will do
Hollow block walls are a network of interconnected voids running from the footing to the top course, and soil gas uses them as a chimney. Treating them means sealing the top course and drawing suction from inside the cavity, usually alongside a sub-slab system rather than instead of one.
Typical cost in Hunterdon County, NJ
$1,800 – $3,200 — typical range, not a quote. What your building needs can only be settled by a certified business that measures it on site.
The credential behind this work
New Jersey licenses this work specifically: a certified radon mitigation business, affiliated with at least one certified radon mitigation specialist. We check the NJDEP register before a crew receives anything from us and we log when we checked. Certifications lapse, so ask to see a current one before you sign anything.
Have a result you don't know what to do with?
Tell us what you've got — a number, an inspection report, or just a house you've never tested. We'll route it to certified crews near you.
Tell us what you've got →Coverage
Towns where this is the right question
Only the ground where this is genuinely the right question — we do not generate a page for a service that makes no sense on a given bedrock.
Highlands ridge and limestone valley
Precambrian gneiss and granite of the Reading Prong, cut by carbonate valleys. The highest-potential ground in the county, and almost all of it on private wells.
Newark Basin shale country
Red shale and mudstone of the Passaic Formation under Flemington and the centre of the county. Fractured rock, plenty of basements, and a mix of public water and wells.
Diabase uplands and the Delaware corridor
Sourland-type diabase and the dark argillite of the Lockatong Formation. Stone farmhouses, open crawl spaces, and river-town cellars cut into rock.